Investigation of submicron aerosol characteristics in Changzhou, China: Composition, source, and comparison with co-collected PM2.5.

Mass concentrations and chemical compositions of submicron particles (PM 1 ) collected during July 2015 to April 2016 in Changzhou, a city in the Yangtze River Delta region, were systematically investigated for the first time. Specifically, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was employed to characterize the water-soluble organic matter (WSOM). The average concentration of PM 1 was 63.6 μg m −3 , occupying ∼60% of co-collected PM 2.5 mass. Water soluble inorganic ions (WSIIs) was the most abundant component with secondary ions (SO 4 2− , NO 3 − and NH 4 + ) as the dominant species. Organic matter (OM) accounted for 21.6% of PM 1 , with approximately 80% was water-soluble. Trace metals could constitute up to 3.0% of PM 1 mass, and Fe, Al and Zn were the three most abundant ones. PAHs were predominated by ones with 5–6 rings, occupying over half of the PAHs mass; further analyses showed that fuel and coal combustion had significant contributions to PAHs. Positive matrix factorization of the WSOM data separated four factors: a traffic-related hydrocarbon-like OA (HOA), a local OA (LOA) likely associated with cooking and coal combustion emissions, etc., a secondary nitrogen-enriched OA (NOA) and an oxygenated OA (OOA). PCA analyses showed that crustal source was likely important for PM 1 too. Back trajectory results implied that both PM 1 and PM 2.5 were mainly derived from local/regional emissions. Our findings present results regarding the PM 1 chemistry and its relationship with the PM 2.5 in Changzhou, which are valuable for the government to make effective policies to reduce the aerosol pollution in and near the city. [ABSTRACT FROM AUTHOR]